Electric furnace



NOV. 13, 1934. A LOPPACKER 1,980,729

ELECTRIC FURNACE Filed Ju1y 26, 1929 Patented Nov. 13, 1934 ELECTRICFURNACE Albert Loppacker, Bloomfield, N. J.

Application July 26, 1929, Serial No. 381,155

9 Claims.

My invention relates to electrically heated furnaces of a type useful,for example, in degassifying metal parts, although, of course, notlimited as to its uses.

A principal object is to provide a simple and economical furnacestructure, and especially to provide means for preserving the heatingcoil by excluding oxygen (or air) and thus preventing oxidation. This isaccomplished by enclosing the inner insulating tube which forms thefurnace chamber and the nichrome wire wound thereon in an outer shellforming a gas chamber to which a suitable gas such as hydrogen issupplied, thus exeluding air and preventing oxidation of the hot wire.The gas chamber surrounding the furnace tube also has a substantialheat-insulating effeet.

The characteristics and advantages of the invention are furthersufliciently explained in con- QW nection with the following detaildescription of the accompanying drawing, which shows one representativeembodiment. After considering this example, skilled persons willunderstand that many variations may be made, and I contemplate ly inlongitudinal section, of a furnace structure embodying the invention inone form.

Fig. 2 is a section at 2-2, Fig. 1.

The heating tube 1 is of any suitable insulating material, such, forexample, as a silicate. It is H formed with a helical groove 2 toreceive the twins of the heating wire, which is usually nichrome. Theheating tube and wire are placed within a tubular shell 3 of metal andof larger diameter, providing a cylindrical gas chamber 4. The ends ofthis chamber are sealed and the inner tube properly positioned by endrings 5 of glass. A small gas supply pipe 6 is fused into the glasssealing ring at one end, and a discharge pipe 7 is similarly sealed intothe glass ring at th other end of the chamber.

A suitable gas, such as hydrogen, is supplied to the chamber to excludeair and prevent oxidation of the heating coil, whose life is therebyindefinitely prolonged.

The ends or terminals 8 of the heating coil are brought out throughholes in the shell with glass insulation 9 therein which also seals theapertures,

I claim:

1. A furnace comprising a tube of insulating material, a heating coilwound thereon, an outer shell dimensioned to provide a gas chamber aboutthe tube, and end sealing rings between the tube and shell, the ringsalso supporting the tube in concentric relation to the shell, and gassupply and discharge tubes passing through the respective sealing rings.

2. A furnace comprising a tube of insulating material, a heating coilwound thereon, an outer shell dimensioned to provide a gas chamber aboutthe tube, and glass end sealing rings between the tube and shell, therings also supporting the tube in concentric relation to the shell, andgas supply and discharge tubes passing through the respective sealingrings.

3. A furnace comprising a tube of insulating material, a heating coilwound thereon, an outer shell dimensioned to provide a gas chamber aboutthe tube, the shell having holes through which terminals of the heatingcoil pass, and insulating and sealing material in the holes about thewire terminals, the gas chamber serving to hold a non-oxidizing gas incontact with the heating coil to prevent oxidation of the heating coil.

4. A furnace comprising a tube of insulating material, a heating coilwound thereon, an outer shell dimensioned to provide a gas chamber aboutthe tube, the shell having holes through which terminals of the heatingcoil pass, and glass insulating and sealing plunger in the holes aboutthe wire terminals.

5. A furnace comprising a tube of insulating material having an externalhelical channel, a heating coil Wound in the channel, an outer shelldimensioned to provide a gas chamber about the tube, and glass endsealing rings between the tube and shell, the rings also supporting thetube in concentric relation to the shell.

6. A furnace comprising an open-ended tube of silicious material, anouter tube larger than the first tube, end sealing rings of glasslocated between the two tubes and sealing the space between the tubes toform a gas chamber, a coil of heating wire wound around the first tube,the ends of the heating wire passing through sealed openings in thewalls of the gas chamber, and gas supply and discharge tubescommunicating with the gas chamber, the gas tubes passing through sealedopenings in the walls of the ga chamber.

'7. A furnace comprising an open-ended tube of silicious material, anouter tube larger than the first tube, end sealing rings of glasslocated between the two tubes and sealing the space between the tubes toform a gas chamber, a coil of heating wire wound around the first tube,the

tube, the tube, shell and sealing members forming a gas chamber, theends of the heatingcoil' passing through sealed openings in the walls ofthe gas chamber, and gas supply and discharge 7 tubes communicating withthe gas chamber, the gas tubes passing through sealed openings in thewalls of the gas chamber.

9. A furnace comprising an open-ended tube of silicious material, anouter shell surrounding and spaced from the tube, glass sealing membersbetween the shell and tube, the tube, shell and sealing members forminga gas chamber, a coil of heating wire wound around the tube, the ends ofthe heating wire passing through sealed openings in the Walls of the gaschamber, and gas supply and discharge tubes communicating with the gaschamber, the gas tubes passing through sealed openings in the walls ofthe gas chamber.

ALBERT LOPPACKER.

